Wire connector with frustoconical gripping spring

ABSTRACT

A plurality of wires are gripped by a frustoconical coil spring which forces the wires tightly against surface portions formed on a rigid member having substantially the same degree of taper as the coil spring. In one embodiment the coil spring is placed within a recess provided in the rigid member and in a second embodiment the spring encircles the rigid member.

United States Patent Inventors John H. Blomstrand 214 Hazel Drive,Corona Del Mar, Calif.

92625; Frederick W. Nyquist, 3318 Via Lido, Newport Beach, Calif. 92660Appl. No. 887,901

Filed Dec. 24, 1969 Patented Oct. 19, 1971 WIRE CONNECTOR WITHFRUSTOCONICAL GRIPPING SPRING [56] References Cited UNITED STATESPATENTS 2,790,962 4/1957 Henderson 174/87 X 3,170,753 2/1965 Witte etal. 339/256 S Primary Examiner-Darrell L. Clay Attorney-Dugger,Peterson, Johnson & Westman ABSTRACT: A plurality of wires are grippedby a frustoconical coil spring which forces the wires tightly againstsurface portions formed on a rigid member having substantially the samedegree of taper as the coil spring. in one embodiment the coil spring isplaced within a recess provided in the rigid member and in a secondembodiment the spring encircles the rigid member.

2a 26 WWII/1110?!!! 1 27 WIRE CONNECTOR WITH FRUSTOCONICAL GRIPPINGSPRING BACKGROUND OF THE INVENTION For instance, U.S. Pat. No.2,714,197, granted July 26, 1955 to Wharton et al. for ELECTRICALCONNECTORS" and U.S. Pat. No. 2,859,424, granted Nov. 4, 1958 to ArthurA. Bemdt for CONNECTOR FOR STRANDED CABLES" both utilize such surfaces.However, these prior art connectors are quite complex and costly tomanufacture.

SUMMARY OF THE INVENTION Accordingly, one object of the presentinvention is to provide a wire connector that will be extremely simple,both as to its construction and also with respect to its use. Morespecifically, an aim of the invention is to avoid any twisting actionthat has heretofore been used in various prior art devices of this type.7

Another object of the invention is to provide a connector for grippingwires. thatcan be manufactured inexpensively, particularly with respectto the assembly thereof.

Another object is to provide a wire connector that will effectively gripseveral wires, yet which will grip one or two wires with equal facilityand effectiveness. In furtherance of this particular object, the coilspring that is employed bears directly against the wires that are to beheld and the various convolutions of the coil spring provide aserrationlike engagemeat with the wires. Consequently, a connector isherein described that will securely hold one, two or three wires oncethey have been inserted and will do so with good electrical contact.

Yet another object is to provide a connector of the foregoing characterhaving a slightly differing taper that provides a gripping action thatprogressively increases with the amount of retractive movement or pullon the retained wires.

A still further object of the invention is to provide a connector forconnecting a plurality of wires together that does not require use ofany implement or tool in accomplishment the connection.

Briefly, the invention comprises a coil spring having a plurality ofresilient convolutions, at least some constituting a frustoconicalsection. In one embodiment, the outer circumference of the frustoconicalspring section engages the wires to be gripped and in a modification ofthe invention the interior of the frustoconical section perfonns theengaging function. In both embodiments, the frustoconical section forcesthe inserted wires against surface areas having a taper correspondinggenerally to, but differing slightly from, that of the frustoconicalsection and any attempt to withdraw the wires increases the wedgingforce so that they are securely held. Specifically, a number of groovesformed in the tapered or frustoconical surface, the number correspondingto the number of wires to be accommodated, guide the wires into theconnector to facilitate their insertion and to assure a positiveretention thereof, especially due to a slightly varying tapered relationimparted thereto.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of oneembodiment our invention may assume, the embodiment accommodating threewires which are in the process of being inserted;

FIG. 2 is a sectional view taken in the direction of line 2-2 of FiG. 1,the view showingthe condition of the coil spring before the wires areinserted;

FIG. 3 is a sectional view corresponding to FIG 2 but illustrating thespring in a gripping relation with the wires;

FIG. 4 is a transversesectional view taken in the direction of line 44of FIG. 3;

FIG. 5 is a perspective view resembling FIG. 1 but depicting a difierentembodiment of the invention;

FIG. 6 is a sectional view taken in the direction of line 6-6 of H6. 5for the purpose of showing the spring prior to gripping the wires;

FIG. 7 is a sectional view corresponding to FIG. 6 but with the wiresheld in a gripped conditions by the springs, and

FIG. 8 is a sectional view taken in the direction of line 8-8 of FiG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to theembodiment illustrated in FIGS. l-4, it will be seen that three wireslabeled 10 have been shown, the wires having stripped or bare ends 12a,12b and 12c.

The wire connector itself has been designated generally by the referencenumeral 14 and comprises a rigid shell or casing 16, preferably ofdielectric material so as to render the connector self-insulating whenused electrically. The shell 16 has an opening at 18 which provides anentrance for the bared wire ends 12a, 12b and into a frustoconical bore22 extending throughout approximately half the length of the shell 16.In the illustrated form, the bore 22 connects with or merges into acylindrical bore 24 that continues for the remainder of the shelllength, that is, to be closed and labeled 25. The interior of the shell16 is formed with three grooves 26 for receiving the several bare ends12a, 12b and 120 which extend the complete length of the frustoconicalbore or surface 22 and also the complete length of the cylindrical boreor surface 24. The grooves 26 have a depth less than the diameter of thewire ends 12a, 12b and 120 which they are to accommodate. It will besomewhat helpful, it is believed, to assign the reference numeral 27 tothe groove bottoms, for the bot tom portion coextensive with the lengthof the frustoconical section 22 form tapered working surfaces thatassist in providing the wedging action hereinafter more fully explained.Although not perceptible from the drawings, the bottoms 27 divergeslightly (about 0.004 inch per inch of connector length). Statedsomewhat differently the groove bottoms possess a rate of taper somewhatgreater than that of the bore 22, that is they get deeper in a directionaway from the opening 18. For a purpose made manifest immediately belowa cylindrical lug 28 is fonned integrally with the bottom 20.

Having mentioned the lug 28, attention is now directed to a resilientcoil spring 30 having a number of convolutions 32 that progressivelyincrease from a relatively small diameter at one end labeled 34 to arelatively large diameter at 36. More specifically, the degree of tapercorresponds to that of the bore 22 but differs slightly from the groovebottoms 27 (because the taper of the groove bottoms difiers from that ofthe bore 22, as explained above). The convolutions denoted by thereference numerals 34 and 36 reside at opposite ends of thefrustoconical coil spring section 32. The coil spring 30 additionallyincludes convolutions having the same diameter as the convolution 36,thereby forming a cylindrical section labeled 38. In the presentembodiment some of the convolutions forming the cylindrical section 38are passed onto the lug 28 and in this way the coil spring 30 isanchored within the shell 16 in preparation for the insertion of thewire ends 12a, 12b and 12c.

The manner in which our connector 14 is used should be readilyunderstood from the information already given. It will be appreciatedthat the user need only insert the bare wire ends 12a, 12b and 120 intothe various grooves 26, doing so through the opening 18. Such actionwill cause the ends 12a, 12b and 120 to abut the convolution 34 andfurther movement will compress the coil spring 30. Stated somewhatdifferently, the smaller convolution 34 is urged to the right, therebyincreasing the clearance between the bottoms 27 of the grooves 26 andthe exterior of the convolution 34, as well as the other convolutionsconstituting the frustoconical section 32. The

coil spring 30 will only compress to the extent necessary to permit thewire ends 12a, 12b and 12c to be received and the biasing tendency forthe spring 30 to return to its original length causes the wire ends 12a,12b and 120 to be pressed outwardly against the groove bottoms 27.

Once received in the grooves 26, any attempt to retract the wire endswill be resisted by virtue of the fact that the frustoconical springsection 32 will urge or wedge the wire ends more forcibly outwardlyagainst the bottoms 27 of the several grooves 26. Each action is mademore positive by reason of the slightly differing taper imparted to thegroove bottoms 27 with respect to that of the frustoconical section 32.Additionally, the rounded cross section or outer curvature of eachconvolution of the section 32'functions as a tooth, bearing tightlyagainst the bare wire ends 12a, 12b and 120 in a serrationlike fashionto provide further assurance against inadvertent removal or retractionof the wire ends. Consequently, the wire are firmly gripped by theconnector 14.

It will be appreciated that all three wires 10 need not be gripped, forif only one wire 10, say the onehaving the bare end 120, is inserted,the action is the same because any attempt to retract or withdraw thewire end 12a will pull the conical section 32 therewith and will wedgethe wire end 12a against the bottom 27 of the particular groove 26 inwhich this end is received. The same retentive or wedging action existswhen only two wires 10 are to be held.

Although it is believed evident, the lug 28 need not exert any realdegree of retentive force against the cylindrical section 34 of the coilspring 30, for once the wires have been inserted, the wedging actionitself prevents the coil spring 30 from being retracted. In other words,it is only prior to the actual use of the connector 14 that the lug 28performs a worthwhile function. It merely keeps the coil spring 30 fromshifting within the interior of the shell 16 until the wires have beeninserted, so it is not essential that the lug 28 fixedly hold I thespring, thus facilitating its assembly, as the spring can be readilyintroduced through the opening 18 and simply pressed onto the lug 28.

Describing now the modification appearing in FIGS. 5-8, it will bediscerned that this embodiment has been designated in its entirety bythe reference numeral 50. A casing or shell 52 is employed and ispreferably of dielectric material so that it can be used in variouselectrical environments without having to cover it with insulation.Providing an entrance at one end for the bare ends 12a, 12b and 12c isan opening 54 leading into a cylindrical bore 56 extending generallythroughout the length of the entire shell 52, the closed end thereofhaving been assigned the reference numeral 58. I

Contained within the bore 56 is a plug or insert 60. The plug 60 may beof metal or plastic and is formed with a frustoconical surface 62 thatdecreases in diameter from one end indicated by the reference numeral 64to the other end labeled 66. The plug 60 is formed with an annularflange 68 that is embedded in the material constituting the shell 52 andthe plug 60 is in this way fixedly held within the shell 52. The flange68 is provided with three holes 70, each communicating with one end ofseveral grooves 72 formed in the frustoconical surface 62. It is throughthe holes 70 that the bare ends 12a, 12b and 120 are inserted in thepresent instance. The bottom of each groove 72 has been designated bythe reference numeral 75 and possesses a slightly increased degree oftaper as compared with the frustoconical section 62, that is they getdeeper toward the smaller end 66 of the plug 60.

A resilient coil spring 74 encircles the frustoconical surface section62, having a section 76 that tapers to the same degree as thefrustoconical surface section 62, but not quite as much as the groovebottoms 75. The section 76, to describe itslightly differently, iscomposed of a number of convolutions, the larger convolution 78 being atthe left and the diameter of the convolutions progressively decreasingtoward the other end of the frustoconical section 76, the smallerconvolution at the other end of the section 76 having been given thereference numeral 80. In the illustrated instance, a cylindrical section82 of the coil spring 72 continues toward the closed end 58 of the shell52 and abuts thereagainst.

In use, the action derived from the connector 50 is generally similar tothat obtained when using the connector 14,

- although the construction thereof is quite different. In the use aneven greater increase with respect to the bottom 75 of the I variousgrooves 72 (owing to the different rate of taper). When the bare ends12a, 12b and have been inserted suffciently, then further compression ofthe coil spring 74 ceases, but any attempt to retract the wires 10 willresult in the convolutions constituting the frustoconical section 76being pulled in the direction of attempted retraction with theconsequence that the resulting wedging action increases with the amountof retractive effort. A positive retention of the wire ends 12a, 12b and120 is thereby provided with the connector 50 as with theearlier-described connector 14.

We claim: I

1. A wire connector comprising a resilient coil spring member composedof a number of convolutions, at least some of said convolutions fonninga frustoconical section increasing from a smaller diameter at one end toa larger diameter at the other end, and a rigid member formed with afrustoconical surface having a groove therein providing a slopingsurface having a taper corresponding generally to that of said springsection, said frustoconical spring section being within thefrustoconical surface of said rigid member so that said sloping surfaceis juxtaposed in a coacting relationship with said spring section,whereby said spring member may be longitudinally compressed to increasethe clearance between said sloping surface and said spring section toreceive therebetween a wire to be gripped.

2. A wire connector comprising a resilient coil spring member composedof a number of convolutions, at least some of said convolutions forminga frustoconical section increasing from a smaller diameter at one end toa larger diameter at the I tending grooves of a depth less than thediameter of the wire to be held, said several grooves being angularlyspaced with respect to each other, whereby insertion of the wire intoone of said grooves via said open end of said shell member willlongitudinally compress the coil spring member to an extent that theclearance between the bottom of said groove and the convolution near theend of the groove via which the wire is inserted is equal to thediameter of the inserted wire.

3. A wire connector in accordance with claim 2 in which said groovesbecome deeper in a direction away from the ends thereof via which thewires are inserted.

4. A wire connector in accordance with claim 1 in which said shell is ofdielectric material.

5. A wire connector in accordance with claim 2 in which the end oppositethe smaller end of said coil spring is anchored with respect to theclosed end of said shell.

6. A wire connector comprising a shell open at one end and closed at theother end, a resilient coil spring member composed of a number ofconvolutions, at least some of said conend thereof, and a rigid memberformed with a frustoconical I surface section also increasing from asmaller diameter at one end to a larger diameter at the other endthereof, said frustoconical surface section having severallongitudinally extending grooves of a depth less than the diameter ofwire to be held, said rigid member constituting a plug having an annularflange extending outwardly and anchored in the shell near the open endthereof, said flange having a plurality of holes therein for theinsertion of a plurality of wire ends into said several grooves, saidplug having formed exteriorly thereon said frustoconical surface whichcontains said grooves and said grooves being aligned with said holes insaid flange, the frustoconical section of said spring tapering from alarger diameter near said flange to a smaller diameter adjacent saidclosing end and said smaller diameter end abutting against the closedend of said shell, whereby insertion of the wires into said grooves viasaid one end will longitudinally compress said coil spring member to anextent that the clearance between the bottom of said grooves and theconvolution near the end of the grooves via which the wires are insertedis equal to the diameter of each inserted wire.

7. A wire connector in accordance with claim 6 in which said shell is ofdielectric material.

8. A wire connector comprising a dielectric shell member open at one endand closed at its other end, a rigid plug element within said shellhaving outwardly projecting means thereon at one end anchored to saidshell member near its said open end and tapering to a smaller end nearthe closed end of said shell, said plug element having at least onegroove extending from the larger or anchored end thereof toward its saidsmaller end to provide a tapered surface, a resilient coil spring membercomposed of a number of convolutions, at least some of said convolutionsforming a frustoconical section encircling said plug element andtapering from a larger diameter adjacent said projecting means to asmaller diameter toward the smaller end of said plug element, the taperof said spring section corresponding generally to that of said groovesurface, whereby a wire may be inserted into said groove via the openend of said shell member and said spring longitudinally compressed toincrease the clearance between said sloping surface and said springsection to receive and grip said wire therebetween.

9. A wire connector in accordance with claim 8 in which said anchoringmeans includes an annular flange embedded in the shell member, saidflange having a hole aligned with said one. groove, and in which thesmaller end of said coil spring abuts the closed end of said shellmember.

1. A wire connector comprising a resilient coil spring member composedof a number of convolutions, at least some of said convolutions forminga frustoconical section increasing from a smaller diameter at one end toa larger diameter at the other end, and a rigid member formed with afrustoconical surface having a groove therein providing a slopingsurface having a taper corresponding generally to that of said springsection, said frustoconical spring section being within thefrustoconical surface of said rigid member so that said sloping surfaceis juxtaposed in a coacting relationship with said spring section,whereby said spring member may be longitudinally compressed to increasethe clearance between said sloping surface and said spring section toreceive therebetween a wire to be gripped.
 2. A wire connectorcomprising a resilient coil spring member composed of a number ofconvolutions, at least some of said convolutions forming a frustoconicalsection increasing from a smaller diaMeter at one end to a largerdiameter at the other end thereof, and a rigid shell member closed atone end and open at the other end increasing from a smaller diameter atits open end to a larger diameter at its closed end, said coil springmember being received within said shell member so that the smallerdiameter end thereof is near the open end of said shell member and thelarger diameter thereof is adjacent the closed end of said shell member,said frustoconical surface secton of said shell member having severallongitudinally extending grooves of a depth less than the diameter ofthe wire to be held, said several grooves being angularly spaced withrespect to each other, whereby insertion of the wire into one of saidgrooves via said open end of said shell member will longitudinallycompress the coil spring member to an extent that the clearance betweenthe bottom of said groove and the convolution near the end of the groovevia which the wire is inserted is equal to the diameter of the insertedwire.
 3. A wire connector in accordance with claim 2 in which saidgrooves become deeper in a direction away from the ends thereof viawhich the wires are inserted.
 4. A wire connector in accordance withclaim 1 in which said shell is of dielectric material.
 5. A wireconnector in accordance with claim 2 in which the end opposite thesmaller end of said coil spring is anchored with respect to the closedend of said shell.
 6. A wire connector comprising a shell open at oneend and closed at the other end, a resilient coil spring member composedof a number of convolutions, at least some of said convolutions forminga frustoconical section increasing from a smaller diameter at one end toa larger diameter at the other end thereof, and a rigid member formedwith a frustoconical surface section also increasing from a smallerdiameter at one end to a larger diameter at the other end thereof, saidfrustoconical surface section having several longitudinally extendinggrooves of a depth less than the diameter of wire to be held, said rigidmember constituting a plug having an annular flange extending outwardlyand anchored in the shell near the open end thereof, said flange havinga plurality of holes therein for the insertion of a plurality of wireends into said several grooves, said plug having formed exteriorlythereon said frustoconical surface which contains said grooves and saidgrooves being aligned with said holes in said flange, the frustoconicalsection of said spring tapering from a larger diameter near said flangeto a smaller diameter adjacent said closing end and said smallerdiameter end abutting against the closed end of said shell, wherebyinsertion of the wires into said grooves via said one end willlongitudinally compress said coil spring member to an extent that theclearance between the bottom of said grooves and the convolution nearthe end of the grooves via which the wires are inserted is equal to thediameter of each inserted wire.
 7. A wire connector in accordance withclaim 6 in which said shell is of dielectric material.
 8. A wireconnector comprising a dielectric shell member open at one end andclosed at its other end, a rigid plug element within said shell havingoutwardly projecting means thereon at one end anchored to said shellmember near its said open end and tapering to a smaller end near theclosed end of said shell, said plug element having at least one grooveextending from the larger or anchored end thereof toward its saidsmaller end to provide a tapered surface, a resilient coil spring membercomposed of a number of convolutions, at least some of said convolutionsforming a frustoconical section encircling said plug element andtapering from a larger diameter adjacent said projecting means to asmaller diameter toward the smaller end of said plug element, the taperof said spring section corresponding generally to that of said groovesurface, whereby a wire may be inserted into said groove via the openend of said shell memBer and said spring longitudinally compressed toincrease the clearance between said sloping surface and said springsection to receive and grip said wire therebetween.
 9. A wire connectorin accordance with claim 8 in which said anchoring means includes anannular flange embedded in the shell member, said flange having a holealigned with said one groove, and in which the smaller end of said coilspring abuts the closed end of said shell member.